kelly



2 Sheets-Sheet 1.

(No Model.)

J. F. KELLY.

ELEOTRIGAL CURRENT INDICATOR.

Patented Nov. 8, 1887.

- WITNESSES: fmwx g, 14 Ma PM, 3Q

l/VVE/VTOH I? 5y 471mm, wn/Z2 P Arm/MUS, v

(No Model.) 2 Sheets-Sheet 2.

J. P. KELLY.

ELECTRICAL CURRENT INDICATOR. No. 372,851. Patented Nov. 8, 1887.

WITNESSES;-

ATTORNEY 8 N. PETERS, Pholmulhognwmr. Washlngtbn, D. (1

JOHN F. KELLY, OF HOBOKEN, NEW

PATENT @EErcE.

JERSEY, ASSIGNOR TO THE UNITED STATES ELECTRIC LIGHTING COMPANY, OF NEW YORK, N. Y.

ELECTRICAL-CURRENT INDICATOR.

SPECIFICATION forming part of Letters Patent No. 372,851, dated November 8, 1887.

Application filed December 1, 1886.

To aZZ whom it may concern:

Be it known that I, JOHN F. KELLY, a citizen of the United States, residing at Ho'- boken, in the county of Hudson and State of New Jersey, have invented certain new and useful Improvements in Current-Indicators, of which the followingis a specification, reference being had to the drawings accompanying and forming a part of the same.

[O This invention is an improvement in that class of electrical instruments which are used for indicating the amount or strength of currents, and is designed for use as an ammeter. The invention consists in improvements in the I 5 construction of the instrument, which render it more durable and generally more efficient and practicable than others of its class.

Said improvements consist, first, in the employment, in combination with a field-magnet,

of a soft-iron armature-plate pivoted in proper relation to said magnet and divided up by slots 1 into numerousparts, by means of which the direction of the lines of force is determined and the effects of residual magnetism reduced to a minimum; and, second, in a peculiar and novel construction and adaptation of the several parts of the apparatus that renders the same more serviceable for usewith circuits carrying heavy currents.

These improvements are illustrated in the accompanying drawings, in which Figure 1 is a side elevation of the instrument with the armature and one of its supports omitted; Fig. 2, a vertical broken section of the same; Fig. 8, a cross-section of Fig. 2, taken justbelow the magnetcores; and Fig.

4, a side elevation of the armature and indicator-needle.

Theinstrument is secured to a vertical support by means of brackets A A. To the upper plate or bracket, A, the cores B G are secured by screws c,which pass through the condnctors surrounding the cores and areinsulated from them. The cores are flat iron plates built up of a number of thin strips laid one upon another and bound together by rods and screws d, passing through holes in the strips near their ends. These cores are surrounded by the coils,whi'ch in the present instance consist of two fiat copper bands, D E. Each one of these bands is bent so as to fit over the cores,

Serial No. 220,364. (No model.)

as shown in Fig. 2. They are placed over the cores near their ends, and are connected together in series and so as to co-operateinmagnetizing the cores by a cross-strip, F,clamped 5 5 to the ends of the bands, as shown in Fig. 3. The ends of the bands D E that form the terminals of the instrument are provided with sockets of metal G G, which are either united to the bands or cast in one piece with them.

To the bands D E are secured cross-bars H, one of whichis shown in Fig. 1. These bars are insulated from the bands, and are provided with bosses K, through which pass'pivotingscrews L. By means of these screws the armature and pointer are supported between the cores.

The armature is a fiat soft-iron plate or bar, M, pivoted at its center and divided up into a number of parts or sections by the slots N. The object of this is to determine the direction of the lines of force and to weaken the residual magnetism, so that it may not interfere with the proper working of the instrument. The sameresult may be obtained by dividing up the 7 said plate in other similar and well-known ways. To the plate itself, or to ashort spindle passing through it, is secured a pointer,O, for which a proper scale, P, is provided, and an adjustable weighted arm, R, serving as a counterpoise.

The plate, pointer, and counterpoise are set at different angles to each other in the same or parallel planes. The normal position of the armature is with its longer dimension nearly at right angles to the line joining the poles of the cores. When in this position, the pointer is on the zero-mark of the scale; but the armature will be more or less shifted by magnetic attraction, its deflection increasing with the 0 strength of the current acting on the cores, so that the pointer will indicate by its position the strength of current flowing.

The abovedescribed apparatus forms a very sensitive and accurate current-indicator, and 5 has the advantage of not requiring a permanently-magnetized armature. When ouceadjusted, therefore, it requires no further attention, as the opposing forcegravitywill be always practically the same. The bars con- IOO stituting the coils in this case may be insulated from the cores in any convenient manner, and

may vary in size and number. In small ininto a number of purt-s,of iron cores on opposite struments the ordinary coils will be preferable; sides of the plate, and copper bands bent so as VVhatI now claim is to surround the sides and upper edges of the 1. In a current-indicator, an armature supcores, and provided with sockets or means for 5 ported in a magnetic field formed by magnetic connecting them with the wires of a, circuit, as I5 plates surrounded by coils or bars, and consistherein set forth.

in g of a centrally-pivoted soft-iron plate slotted JOHN F. KELLY. ordivided in substantially the mannersetfort-h. Witnesses:

2. The combination, in a current-indicator, CHAS. E. BALDWIN, 10 with a pivoted iron plate slotted or divided up MosEs J. DE WVITT. 1 

